Many magnetically stabilized fluidized bed (MSB) processes are operated with the direction of solids flow transverse to the flow of an ascending or upward moving fluidizing fluid. Examples of such processes include particulates capture, solids/solids separations and continuous chromatographic separations. In such processes, it is necessary to recycle (often via additional process steps) the bed solids from the outlet to the inlet of the bed. Usually, this is achieved pneumatically or hydraulically using fluid risers or mechanically using bucket elevators. However, such transport methods often result in excessive particle attrition and elutriation, and usually represent a major cost of the operation. In addition, using such solids transport methods to recycle bed solids often results in an increased bed depth near the point at which the solids are reintroduced into the bed and for a substantial distance along the flow direction of said bed. This gradient in bed height may result in fluid maldistribution leading to poor fluid-solids contacting and potential bed destabilization. Also, costly and complex equipment is involved in such methods of solids circulation, which adds appreciably to the overall investment and energy requirements of the operation.
The use of fluid jets to move solid objects and fluidized powders has been disclosed previously (See, for example, U.S. Pat. Nos. 3,131,974; 3,180,688; 3,304,619; Futer, R. E. "Conveying Solids With Cooperating Series of Air Jets," ASME Symposium on Flow of Solids, Boston, Mass., Oct. 20-23, 1968 (Paper No. 68-MH-31); Shinohara, K. and Tanaka, T., "A New Device for Pneumatics Transport of Particles," J. Chem. Eng. of Japan, 5, 279 (1972); and Woodcock, C. R. and Mason, J. S., "Air Gravity Conveying: Fluidize Your Powder and Let it Slide," International Powder and Bulk Solids Handling and Processing Conf. Proceedings, Philadelphia, Pa., May 15-17 (1979), the entire disclosure of each publication being incorporated herein by reference). In the devices disclosed therein, the jets are directed such that the entering fluid has an appreciable component of velocity in the direction of desired solids movement. As such, momentum is transferred to the solids upon contact with said entering fluid. When used in conventional fluidized beds, the fluid not only imparts motion to the solids, but also provides the fluidizing means. However, in conventional fluidized beds, employing the fluid in such a manner may cause excessive and unacceptable attrition and elutriation of the bed solids, fluid bypassing and solids backmixing in both the vertical and horizontal directions, thus decreasing the contacting efficiency of the process.